Aug. 9, 1949. A. v. MAsKET ET AL 2,478,663

PROJECTILE TESTING MACHINE Filed March 29, 1946 2 Sheets-Sheet l 'lllllll AlfEERT-/:MAE KET,l .LELAN D EL 5 N EDDY, JE55-EWEEAM5,

Aug 9, 1949- A. v. MAsKET ET Al. 2,478,663

PROJECTILE TESTING MACHINE Filed March 29, 1946 2 Sheets-Sheet- 2 lu/umm .ALBERT VMAEKET, l LELANDELEI NDDDY, J5EE' EWEEAME.,

Patented Aug. 9, 1949 PRGJECTILE TESTING MACHINE Albert V. Masket, Leland B. Snoddy, and Jesse W. Beams, Charlottesville, Va.

Application March 29, 1946, Serial No. 658,304

(Cl. 7S-66) 4 Claims.

This invention yrelates to a pneumatic device for spinning at high velocities objects such as bullets and artillery shells in order to test their stability. The objects are rotated on an axis of symmetry, free of any direct mechanical connection or thrust, by the action of an air jet.

An object of this invention is to provide means for spinning at high speed on its geometric axis, a bullet or an artillery shell, in order to test its degree of dynamic unbalance.

A Afurther object is to provide means for automatically indicating an unsatisfactory degree of unbalance of the spun object, so as to provide means enabling routine inspection of same. Another object is to spin at high speed on their geometric axis, ballistic objects such as artillery shell fuzes so as to permit study or routine inspection of the action of the arming pin at high speed. Further purposes will become evident from the following descriptions and claims.

The present best use of our invention appears to be in the selection of high grade bullets for small arms ammunition, the selection being made on the basis of dynamical asymmetry about the geometric axis. A bullet which is dynamically asymmetrical about its geometric axis is unbalanced so that its axis of spin in flight is not coincident with its geometric axis. There is ample evidence that the spread of a pattern of bullets red at a target can be correlated with the amount of dynamic unbalance of the individual bullets.

It is therefore important when special accuracy of nre is required that the bullets used be in substantial dynamic balance.

In the drawings:

Figure 1 is a Lfront elevation in partial section on line I-I of Figure 2 of a preferred embodiment of our invention,

Figure 2 is a sectional view on line 2-2 of the device shown in Figure 1,

Figure 3 is a plan view of the stator and associated contact making means of Figure 1,

Figure 4 is a sectional view taken on line A--d of Figure 3,

Figure 5 is a sectional view taken on line 5-5 of Figure 3,

Figure 6 is a sectional view taken on line 6--6 of Figure 3,

Figure 7 is a disassembled perspective view of the stator showing the stator retainer and contact strips.

Essentially our invention consists of a hor-izontal stator or trough dimensioned to receive the bullet or other object to be tested, and perforated in a plane normal to its axis to provide an eccentrically disposed jet through which a stream of air or other gas under pressure strikes eccentrically against :a bullet placed in the trough. The rapid streaming ofair around the bullet provides torque to spin the bullet, and also generates suiiicient Bernoulli force to keep the bullet in place due to the stabilizing effect of zones of diminished pressure resulting from the high velocity of the contracted stream of escaping gas, both in the circumferential and in the axial directions. The stator is flexibly mounted to permit vibration thereof, which will be imparted to it by either staticV or dynamic unbalance of the bullet. If vibration of the stator exceeds a predetermined amount, the bullet is rejected as unsatisfactory. In the embodiment shown, for routine inspection purposes a contact between a member fixed to the stator and an adjustable stationary member is used to close a signal'circuit to indicate that the bullet being tested is unsatisfactory.

Referring to the iigures, the stator I, preferably of light plastic or similar material, is drilled at 2 to provide an eccentrically disposed jet, and is exibly mounted on an air hose 3 which furnishes air under pressure to jet 2 through air hose extension 4, which is firmly fastened to the air house by clamp 5. Air hose 3 is made of rubber or any suitable material of similar characteristics and is firmly held by a rigid tube 6 which passes through a hole in metal support plate 1 to position the stator. A certain amount of stator vibration is thus permitted due to flexibility of air hose 3.

Stator retainer 8, best seen in Figure 7 is fastened to the stator I by any suitable means such as screws. This retainer serves to reinforce the stator I. Contact connecting strip 9 and -contact strip I0 are .fastened to stator I by screw II. Contact connecting strip 9 is provided with a binding post I2 for connection of lead I3 from the signalling circuit. This circuit leads from plug I4', which may -be connected to any suitable source of electricity, through lead I3, connecting st'rip 9 and contact I0, which upon suicient vibration of stator I will make at least intermittent' contact with contact point I4.

An inexpensive micrometer I5 maybe cut down to provide an adjustable contact point I4, thereby permitting ne gradation in adjustment to be made, or a ne contact point adjustment may be provided by any other known means. In the embodiment shown we use a micrometer suit- 3 a-bly cut down and screwed to a mount I6 which is in turn fastened to support 'plate I (Figure 6).

The signal circuit continues from contact point I4, through the micrometer and mount IS and plate 1 to binding post l1, through lead IB to switch I9 thence through lead 20 to signal lamp 2| and through lead 22 back to plug lll.

The entire assembly is mounted in a housing 23 provided vttht adjusting legs.2'4toppermit leveling of stator I. "Two lead platesare "shown one on either side of the bottom o1 box 23, to add stability and to aid in absorbing vibrations.

The side 24 containing the signalflampl. and the side 25 containing the stator and contacts are hinged at 26 and 21 respectively tofa'c`ilit'ateac-Y cessibility. Hooks 28 and 29 cooperatingfyvith brads 28a and 29a respectively arefshownnfor keeping the respective hinged sides closed, a1- though it is obvious that any other-suitable fastening means may be used.

.':Itwill heapparentmhat itheicontact means are prmridedz for; fconveniencezgin lroutine .finspection .-ftand that:Nisualiobsenvationr'off,the vibration of i the .'statorz'will` provdeuusefultinfnrmation regardiing theA stability of thefbullet. Also,fstroboscopic -L-inspdction of lthe: builetrflby; known means, Vcan be nntilized tot provide: detailed :information regard- 2 ing'nsthee angular cfpnsition Kofi' unbalanced of i :the rfbullet.

.We: claim:

f 1,iA spinning device frfor @testing *dynamic noalance:comprising; aA 'stator' having a curved i innerrsurface:` comprising; etihorizontally disposed tttrough ziiimensioned.dao:` receive *an-fy object :to be testedntherezbeing acjetonrice inv thestator; r eccentricallyuiiisposd relative .ato `fthe 'axis 1' of :icurvature `of;saidistattorssurface and'jcommunicat- .'ingrwith. 'ther curvedr inner -surface,imeans for ntsupplyingfgas underapressure. zto-said jet rorifice f andi-flexible :supportzmeans for Isaid stator.

-;.2..A @spinning cdevice for :Jtesting .idynamic balance comprising; a stator havingfaL curved ffinnensurface dimensioned :to receive anf object to becftested f andA Aformingfia l1orizontal1y disposed fftronghtlof.-vvhichr one; horizontale-edge ishigher than the otherzhorizontal edge; there -heing a:jet oriiice in the fstator -eccentricallyi disposeditoward the isaid".highery edgefin a lplane normal tothe .zA-supporting meanszfonsaid staton-tandzmeans for supplying gas `,under pressure to. said .jet orce to said stator, a second contact normally spaced from said first contact but arranged to fbe contacted by said first conta-ct upon a predetermined degree of vibration of said stator, an electric cir- 'cnitrinclu'dingaa signalalamp and said contacts,

l0J *saidfcircuitvbeing so arranged as to be closed upon the touching of said contacts, whereby a predetermined degree of vibration of said stator may ,berfindicatedby the closing of the signal lamp circuit.

: 24.l-"fAsg-'spinning`1device for testing dynamic f-fbalance comprising; a horizontal stator having a .curvednnensurface dimensioned to receive an object to be tested, there being a jet orifice in the listator eccentrically disposed relative to the axis of curvature of saidi stator surface in a plane inormalrtdaidi axistand'. communicating with the c clawed-inner surf-acemn'eans for-asupplying:A gas .undenrpressureato :saldi-jet orifice; sexihlefsupport meansizfor: said; istatcr, 4anx.electrical circuit? inc .cludingr azisignallingdevice,.` normally fixed contactsmeansi andimovahle' 4contacto means rigidly :i attached-.to said'statorafor cooperating Awith said .axedsconta'ctimeansiwhereby, uponvibration' o1 :f'saidf statorrbeyondr a; predetermined` point said 30 circuit will loe closed.toxsaidielectrcal signalling cdevice, aihousingvior said spinning: device, ad- .;'justable supporting rmeans `for ffsaid f, housing w wherebyssad stator, maybeadjusted to a horiffzontah positions.adjustingLmeans -or Narying 'the '.;distance'rhetweenwsaifrlnormallyxeda and said wibrating contactsgzand ahinged coverifonfsaid frhousing; sainty signallingedevicel beingrsupncrted 1:; upon saidzhinged cover.

L im :.ALBERT V5 MASKET.

.LELAND {B #SNODDY L JESSE NVMBEAMSl REFERENCES- CITED 5 I'The.following` references are of @record in the il file off this-:patent:

l UNITED l' STATES PATENTS wNmhber 'Name Date i 1,'293;984 "iThompson 'Feb. 11; 1919 ;.2,012;780 Taylor ;Aug. 27, 1'935 2,353,150 Dietz July' 11, 1944